Away from work, Mr. Clarke was best known as the bass voice in Boston Common, a barbershop quartet that won the international championship in 1980 — which made him a contender for the Advertising Club’s L.E. Sissman Award. Named for a poet who had been a copywriter at Quinn & Johnson Advertising, the award was presented annually to someone who successfully pursued a creative endeavor outside of advertising.

“I was sitting next to Terry when they called his name,” John Verret, a friend and retired associate professor of advertising at Boston University, recalled in a tribute posted online. “I knew by the look on his face that he was surprised and honored, but his sense of humor took over as he looked at me and said, ‘Great choice, don’t you think?’ And it was a great choice indeed!”

Mr. Clarke, who had run an advertising agency and a public relations firm while teaching at BU, died Feb. 10 from injuries suffered in a fall at a state park in High Springs, Fla., which he was visiting while singing and serving as master of ceremonies at a barbershop quartet event. He was 80 and had been living in Scituate after more than four decades in Hingham.

For years, he headed twin enterprises, which he called “New England’s largest full-service independent public relations agency.” His communications company was Clarke & Co. His advertising agency changed names a few times, but was best known as Clarke Goward. At one point, when the firm was Boston’s eighth-biggest agency, he served simultaneously as chairman, chief executive, and president.

Mr. Clarke also served as a source of inspiration and, when the time was right, impromptu pranks.

“He had this boundless sense of humor, an enormous laugh, and he loved seeing other people succeed,” said Mike Sheehan, a longtime friend who formerly worked at Clarke Goward.

“He had a theory there that I’ve never heard again in the business,” said Sheehan, a former CEO of the Globe and former CEO and chairman of the advertising firm Hill Holliday. “Terry called Clarke Goward a teaching agency, and he likened it to a teaching hospital.”

And indeed, Sheehan added, young advertising professionals tried to get jobs there because “you’ll do really outstanding award-winning work and it will propel your career. Nobody loved to sell really good work as much as Terry did.”

Mr. Clarke started his advertising company and public relations firm in 1977, and their clients ranged from IBM and McDonald’s to Tiffany & Co., Boston Edison, Miller Brewing, the State of Alaska, and crisis communications situations. His PR firm won multiple Silver Anvil Awards from the Public Relations Society of America, and his advertising company took home multiple O’Toole Awards from the American Association of Advertising Agencies.

“He understood the power of a culture, and it was a place where a lot of people wanted to work,” Sheehan said. “It was just a boisterous environment that he participated in. He didn’t approach it as the boss or the owner. He was right in the middle of it. You could tell he was an ex-athlete: It was all about the team.”

Terence Michael Clarke was born at home — delivered by an aunt — in Altoona, Pa., a community for which his affection never dimmed. “The way my dad espoused about Altoona it sounded like Camelot,” said his son Lawson, who lives in Hingham. “He absolutely loved growing up there. He thought the town really took care of its people.”

Mr. Clarke was the third of four children born to Robert Clarke, who ran a heating and air conditioning company and was a state representative, and the former Louise Eckley, a homemaker.

A stellar running back and track star at Altoona High School, Mr. Clarke was a state hurdling champion and received a scholarship to run for the University of Pittsburgh, “where by all his accounts it never really occurred to him that you actually had to go to class,” Lawson said.

Bored one day, Mr. Clarke wandered into an Air Force recruiting office. One thing led to another and before he knew it he had enlisted. He did so well on the entrance exam that the Air Force sent him to the University of Maryland and Yale University, where he became fluent in Mandarin. He was stationed in Japan and, while flying in planes, transcribed intercepted transmissions from China.

Mr. Clarke also persuaded the Air Force to let him compete in track meets abroad. His results were good enough to compete in the 1960 Olympic trials and, when his tour of duty ended, land a scholarship at Boston University. At BU, he graduated with a bachelor’s degree in public relations and a master’s in communications. Over the years, he served as a BU trustee, was president of the Alumni Association, and was an outspoken opponent of the university’s decision in 1997 to discontinue its football program.

When Mr. Clarke taught there for years at night as an adjunct professor, “that booming voice was hard to miss,” Verret wrote. “And there was no missing the energy and enthusiasm of his students when he taught. They loved him, and he loved them.”

After graduating from BU, Mr. Clarke was a communications manager for Pepsi in New York City when he met Judith Lawson, whom he married in 1966. She was a TWA flight attendant who moonlighted at conventions as what was then known as a Pepsi Girl.

Mr. Clarke worked at an agency in Chicago and at H.P. Hood before launching his two companies. Some 14 years ago, his businesses closed amid financial difficulties, and his subsequent move to Providence-based RDW Group ended in publicized acrimony. More recently, he had worked with True North Brand Group in Hingham, where his listing playfully noted that he was “the only respected person on the staff.”

“He was brilliant, funny, charming, sophisticated, down-to-earth, and he had the most eclectic mixture of talents imaginable,” Verret wrote. “He was a true renaissance man.”

A service will be announced for Mr. Clarke, who in addition to his wife and son leaves another son, Penn of South Boston; two sisters, Bridgit Clarke Smith Carlsbad, Calif., and Melinda of Hawaii; and three grandchildren.

Mr. Clarke and the other members of Boston Common were inducted in 2014 into the Barbershop Harmony Society
Hall of Fame. The four men started singing together in 1971, and though they became a highly regarded quartet en route to winning the international championship in Salt Lake City in 1980, they realized their mix of voices was something special right from the beginning, while performing for much smaller audiences.

“We sang everywhere and anywhere,” Mr. Clarke told the Globe in 1973, “in Harvard Square, coffeehouses, and on the Common — mostly for appreciative old ladies and curious students.”